Concrete dowel placement system and method of making the same

ABSTRACT

A concrete dowel placement system and methods for making the same. The system allows for accurate and easy substantially-parallel or parallel placement of slip dowels within sections of concrete so that adjacent sections of concrete may be allowed to undergo thermal expansion and contraction while remaining in a common plane without cracking or faulting. The system includes a coupler and a sheath. The sheath is configured to be slidably extensible over the coupler and may be held to the coupler by friction. Additionally, a method of constructing the concrete dowel placement system includes extruding material to form two tubes of different sizes. The tubes are then attached to each other, then material is extruded to form a sheath. Alternatively, construction may include extruding material to form a tube, then removing some of the material from the tube in order to form a coupler.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND 1. Technical Field

The present disclosure relates generally to a system for use in concreteconstruction and a method for making the system. More specifically, thepresent disclosure relates to a system for placing slip dowels intoconcrete slabs accurately and a method for making the system.

2. Description of the Related Art

In construction, a “cold joint” in concrete may refer to a weakenedinterface between two sections of concrete that harden at differenttimes. Typically, a concrete slab is formed by pouring concrete into aform all at once, where the concrete is allowed to harden. Although,sometimes it is desirable to form a continuous section of concrete bypouring it piecewise in sections at different times, allowing eachsection to harden to some extent before the next adjacent section ispoured and allowed to harden. The interface between a previously pouredsection of concrete and a more recently poured section is called a coldjoint.

A cold joint in concrete is typically weaker under tension than concretethat has been allowed to dry without any cold joints, and this weaknessat the cold joint may cause problems after the concrete hardens. Due tothis weakness, cold joints often become uneven or buckled due to thermalexpansion and contraction of the concrete. Compaction of the underlayingsoil caused by improper substrate preparation before pouring theconcrete can also cause buckling or cracking at the cold joint. Further,too much water moisture may accumulate on the end face of the firstconcrete section before the second concrete section is poured andhardens. If the water freezes, undesirable cracking in the concrete mayoccur due to ice expansion against the concrete. In terms of aesthetics,cold joints often form a visual line at the interface of the twoconcrete sections, which is often undesirable.

To resist buckling, bulging, or displacement of concrete at the coldjoint, it is common to insert long steel rods, known as “slip dowels,”into the edge portions of adjoining concrete sections so that theconcrete sections may slide freely along one or more of the slip dowels.This key feature, the ability to slide freely, may allow linearexpansion and contraction of the concrete sections while substantiallymaintaining the concrete in a common plane, thus preventing undesirablebuckling, bulging, or unevenness at the cold joint.

To function properly, it is typically important to properly position theslip dowels within adjoining concrete sections. For instance, most slipdowels are placed in substantially parallel alignment relative to eachother to allow the concrete sections to slide along the slip dowels.Thus, the purpose of placing the slip dowels may be defeated when thedowels are not positioned in substantially parallel relation to eachother because, in such a case, the concrete sections are not able toslide along the slip dowels. Further, nonparallel placement of slipdowels can cause cracking in the concrete as well as faulting, i.e.,misalignment of the concrete sections at the cold joint. Thus, varioussystems, methods, and devices have been developed for installing slipdowels properly.

In the prior art, two methods of installing slip dowels have becomewidely used. According to the first method, concrete may be poured intoa first form. After the first pour hardens sufficiently, an edge of theform, usually a wooden stud, may be removed. Next, a series of holes,arranged in a straight line, may be drilled into the first concrete slabalong the exposed edge from which the form has been removed. The depthand diameter of the individual holes may vary depending on the purposeof the concrete slabs and the size of the concrete slabs to besupported. Generally, these holes are at least twelve inches deep andtypically have a diameter of approximately five-eighths of an inch,which is complimentary to typical slip dowels having a diameter offive-eighths of an inch.

After the series of holes are drilled into the edge of the first portionof concrete, dowel rods may be inserted into each hole so that one endof each dowel rod is positioned within the first section of concrete.The remainder of each dowel extends into the adjacent area where thesecond slab of concrete is to be poured. Next, concrete may be pouredinto the adjacent area and is permitted to harden with the dowelsinside. After the second section of concrete hardens, the dowels areheld firmly within the second section, but are permitted to slidelongitudinally within the drilled holes of the first section. Thisallows longitudinal expansion and contraction of the two concretesections while at the same time preventing buckling or faulting at thecold joint.

The “drilling method” of placing slip dowels described above is verylabor intensive. It can take about ten minutes to drill a five-eighthsinch diameter by twelve inches long hole into the first concretesection. Additionally, the drilling equipment, bits, accessories, andassociated setup time tends to be very expensive. Moreover, theconstruction workers who drill the holes and place the slip dowels musthave sufficient training to ensure generally parallel arrangement ofeach dowel to the other dowels and to the underlying support surface.

A second widely-used method of placing slip dowels involves usingwax-treated cardboard sleeves positioned over one end of each individualdowel. By this method, a series of holes may be drilled through one edgeof a concrete form and smooth dowels may be inserted through each hole.Wax-treated cardboard sleeves may be placed over one end of each doweland the first pour may be made within the form. After the first pourhardens, the previously-drilled form may be stripped away, leaving theindividual dowels extending into the adjacent open space where thesecond pour is to be made. Subsequently, the second pour may be made andallowed to harden. As a result, the slip dowels are held firmly by theconcrete of the second pour but are permitted to slide longitudinallyagainst the inner surfaces of the wax-treated cardboard sleeves withinthe first concrete section. Thus, the waxed cardboard sleeves facilitatelongitudinal slippage of the dowels, while at the same time holding thetwo concrete slabs in a common plane, preventing undesirable buckling orangular movement at the cold joint.

Although this second method is widely used, it is commonly associatedwith a variety of problems. For example, after the first pour is made,the free ends of the dowels are likely to project as much as eighteeninches through the forms and into the adjacent open space allowed forthe second pour. Because the drilled section of the form must be slidover those exposed sections of the dowels to accomplish stripping orremoval of the form, it is not uncommon for the exposed portions of thedowels to become bent, and thus, not substantially parallel. Also, thedrilled section of the form may become damaged or broken during theremoval process, thus preventing its reuse.

Unfortunately, both of the popular methods of placing slip dowelsdiscussed above often cause the slip dowels to be positioned at variousangles rather than in the desired aligned arrangement. When this occurs,the necessary slippage of the slip dowels is impeded or prevented andthe likelihood of cracking and faulting in the concrete increases.

Alternative prior art dowel placement devices may comprise elongated,hollow tubes sized to receive portions of dowel rods. The tubes may bemounted to one edge of a concrete form in generally parallel relation toeach other via integral base portions. Next a first concrete pour may bemade over the tubes. After the first pour hardens, the edge of theconcrete form to which the tubes are mounted may be stripped away fromthe first slab. Then, dowel rods may be inserted into the exposed openends of the tubes embedded within the first slab. The portions of thedowel rods not inserted into the tubes extend into an adjacent areawhere a second pour of concrete may be made. Concrete poured into theadjacent area completely covers the outer surfaces of the dowel rodswhich are held firmly within the second slab formed when the second pourhardens. The dowels, though being held firmly within the second slab,are permitted to slide longitudinally within the tubes embedded in thefirst slab.

Even though these prior art placement devices have advantages over thepreviously described dowel placement methods, several disadvantagesinhibit their usefulness. In particular, the attachment of the baseportions of these prior art placement devices to a concrete form oftenrequires the use of multiple fasteners, making the attachment processdifficult and time-consuming. Additionally, in the prior art placementdevices, both the tube and its integral base portion used to facilitatethe connection of the tube to the concrete form are embedded in thefirst slab, thus necessitating that additional placement devices beattached to the concrete form prior to its reuse. Further, the prior artplacement devices are generally only suited for attachment to a concreteform, and not to reinforcement materials, such as rebar or wire mesh. Assuch, these prior art placement devices do not lend themselves to usewithin the interior areas of a poured slab, but rather are limited touse along the periphery of the slab which is defined by the concreteform to which the placement devices must be attached.

Another problem with prior art concrete dowel placement devices is thehigh manufacturing cost. Prior art placement devices have beenmanufactured using injection molding. Injection molding can be costprohibitive and have other problems innate with the method itself. Suchproblems include burning of the material being molded, thus weakeningits final structure; flashing, i.e., excess molded material attached tothe molded product which requires extra time and effort to remove; andshort shotting, i.e., when a region of the mold lacks sufficientquantity of injected material, resulting in a physical deformity in thefinal molded product.

Accordingly, there remains a need in the art for methods and/or systemsfor facilitating the proper placement of slip dowels, and methods formanufacturing such placement systems, which overcome the previouslydescribed deficiencies associated with prior art placement devices andsystems.

BRIEF SUMMARY

The present disclosure specifically addresses and alleviates theabove-identified deficiencies in the art. In this regard, the disclosureis directed to a concrete dowel placement system and method of makingthe concrete dowel placement system. As will be discussed in more detailbelow, the method allows for cost-efficient manufacturing of the system.The concrete dowel placement system allows for easy and accurateplacement of slip dowels into concrete.

According to one embodiment, a method of constructing a concrete dowelplacement system includes the step of constructing a coupler. The stepof constructing a coupler includes the step of extruding a polymer toform a first tubular element. The step of constructing a coupler alsoincludes the step of extruding a polymer to form a second tubularelement, the second tubular element having a dimensional size differentfrom a dimensional size of the first tubular element. The step ofconstructing a coupler additionally includes the step of attaching anend portion of the second tubular element to an end portion of the firsttubular element. Further, the method includes the step of extruding apolymer to form an elongated, tubular, dowel-receiving sheath, thesheath having at least one interior opening extending along the entirelength of the sheath and the sheath being configured to be slidablyextensible over the coupler to frictionally engage one of the firsttubular element and the second tubular element.

It is contemplated that the method may also include the step ofattaching an end cap to an end portion of the sheath to completely coverthe at least one interior opening at the end of the sheath.

It is further contemplated that the step of extruding a polymer to formthe first tubular element may include forming a body having a circularcross-sectional configuration along a longitudinal axis during extrusionof the polymer. The step of extruding a polymer to form the firsttubular element may include forming the first tubular element to have aninner sleeve and a plurality of splines extending radially outward fromthe inner sleeve and longitudinally along the inner sleeve. The step ofextruding a polymer to form the first tubular element may includeforming the first tubular element to have a quadrangular configurationalong a longitudinal axis during extrusion of the polymer. The firsttubular element may define opposed first tubular element end portionshaving maximum outer diameters approximately equal to each other, andthe second tubular element may define opposed tubular element endportions having maximum outer diameters approximately equal to eachother.

The step of extruding a polymer to form the first tubular element mayinclude forming at least one reinforcement wall between an inner sleeveand an outer sleeve during extrusion of the polymer.

The step of extruding a polymer to form a sheath may include forming atleast one linear rib protrusion, raised helical element, helical grooveelement, or linear groove element along a longitudinal axis of thesheath on an outer surface of the sheath during extrusion of thepolymer. Additionally, this step may include forming a sinusoidal outersurface or a helical uneven outer surface on the sheath during extrusionof the polymer.

Another embodiment of the disclosure relates to a concrete dowelplacement system having a coupler. The coupler includes a first tubularelement having an inner sleeve disposed about a central axis to definean aperture. An outer body is disposed radially outward of the innersleeve. The coupler also includes a second tubular element having aninner sleeve disposed about a central axis to define an aperture. Anouter body is disposed radially outward of the inner sleeve. Theconcrete dowel placement system also has a sheath having an interioropening extending along the entire length of the sheath and beingslidably extensible over the coupler to frictionally engage one of thefirst tubular element and the second tubular element.

The concrete dowel placement system may also include an end capattachable to the interior opening at the end of the sheath tocompletely cover the interior opening at the end of the sheath.

The outer body of the first tubular element may include a plurality ofsplines extending longitudinally along the inner sleeve.

Another embodiment of the disclosure relates to an additional method ofmaking a concrete dowel placement system including the step of extrudinga polymer to form a tubular element. The tubular element has at leastone interior opening extending along the entire length of the tubularelement. The method further includes the step of extruding a polymer toform a sheath. The method may also include the step of forming a couplerby removing some of the polymer from a first length portion of thetubular element so that the first length portion of the tubular elementis of a different dimensional size than a second length portion of thetubular element.

The present disclosure is best understood by reference to the followingdetailed description when read in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the various embodimentsdisclosed herein will be better understood with respect to the followingdescription and drawings, in which like numbers refer to like partsthroughout, and in which;

FIG. 1 is an upper perspective view of an embodiment of a concrete dowelplacement system;

FIG. 2 is a front cross-sectional view of an embodiment of a firsttubular element having four reinforcement walls;

FIG. 3 is an upper perspective view of an extrusion die head having afirst extrusion aperture;

FIG. 4 is an upper perspective view of an extrusion die head have asecond extrusion aperture;

FIG. 5 is a side cross-sectional view of embodiments of a first tubularelement and a second tubular element;

FIG. 6 is a side cross-sectional view of an embodiment of a coupler;

FIG. 7 is a front cross-sectional view of an embodiment of a sheathhaving rib protrusions on an outer surface of the sheath;

FIG. 8 is a perspective view of an embodiment of a sheath having ahelical element on an outer surface of the sheath;

FIG. 9 is a front cross-sectional view of an embodiment of a couplerdisposed within an embodiment of a sheath;

FIG. 10 is a side cross-sectional view of an embodiment of a tubularelement;

FIG. 11 is a side cross-sectional view of an embodiment of a coupler;

FIG. 12 is a side cross-sectional exploded view of the concrete dowelplacement system of FIG. 1;

FIG. 13 is a side cross-sectional view of the concrete dowel placementsystem of FIG. 1 employing a first orientation of a coupler having anouter sleeve of a first diameter at a distal end;

FIG. 14 is a side cross-sectional view of the concrete dowel placementsystem of FIG. 1 employing a second orientation of a coupler having anouter sleeve of a second diameter at a distal end;

FIG. 15 is a side cross-sectional view of the concrete dowel placementsystem of FIG. 13 disposed within a first concrete section;

FIG. 16 is a side cross-sectional view of the concrete dowel placementsystem of FIG. 15 wherein a form section and the coupler have beenremoved;

FIG. 17 is a side cross-sectional view of the concrete dowel placementsystem of FIG. 16 wherein a portion of a slip dowel is disposed withinan interior opening of a sheath;

FIG. 18 is a side cross-sectional view of the concrete dowel placementsystem of FIG. 17 wherein an exposed portion of the slip dowel isdisposed within a second concrete section;

FIG. 19 is an elevational view of another embodiment of a tubularelement and a screw adapted for use as part of a concrete dowelplacement system;

FIG. 20 is a cross sectional view of the tubular element depicted inFIG. 19;

FIG. 21 is a side, partial cross sectional view of a concrete dowelplacement system including the tubular element depicted in FIG. 19; and

FIG. 22 is another embodiment of a coupler adapted for use as part of aconcrete dowel placement system.

Common reference numerals are used throughout the drawings and thedetailed description to indicate the same elements.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of some, but not all, ofcontemplated embodiments of the disclosure, and is not intended torepresent the only form in which the present disclosure may beconstructed or utilized. The description sets forth the functions andthe sequence of steps for developing and operating the disclosure inconnection with the illustrated embodiments.

It is to be understood, however, that the same or equivalent functionsand sequences may be accomplished by different embodiments that are alsointended to be encompassed within the spirit and scope of thedisclosure. It is further understood that the use of relational termssuch as first and second, top and bottom, and the like are used solelyto distinguish one entity from another entity without necessarilyrequiring or implying any actual such relationship or order between suchentities.

Referring to FIG. 1, a perspective view of an embodiment of a concretedowel placement system 10 in accordance with an aspect of the presentdisclosure is illustrated. The concrete dowel placement system 10generally includes a coupler 12, a sheath 14, and an end cap 20. Theconcrete dowel placement system 10 may be used to form a concretestructure.

Now referring to FIG. 2, the coupler 12 includes a first tubular element22 having an outer sleeve 24 and an inner sleeve 26 defining an aperture28 extending along the entire length of the outer sleeve 24. The firsttubular element 22 further includes at least one reinforcement wall 30between the outer sleeve 24 and the inner sleeve 26. The reinforcementwall 30 secures the inner sleeve 26 to the outer sleeve 24 so that theinner sleeve 26 may receive a securing device 18. By way of example andnot limitation, FIG. 2 shows a front cross-sectional view of a firsttubular element 22 that includes four reinforcement walls 30. However,it is also contemplated that the first tubular element 22 may includeany number of reinforcement walls 30.

Referring to FIGS. 3 and 4, the first tubular element 22 may be formedvia extrusion, which may include extruding a material, such as apolymer, preferably a thermoplastic polymer, through a die head 32 toform the first tubular element 22. The extrusion die head 32 may includean extrusion aperture 34. FIGS. 3 and 4 illustrate exemplary extrusiondie heads 32 through which the extrusion of the material may beperformed. Each extrusion die head 32 includes an extrusion aperture 34through which a material is extruded. By way of example and notlimitation, FIGS. 3 and 4 show exemplary extrusion apertures 34 a and 34b where the extrusion apertures 34, in minor part, or substantiallydefine the cross sectional shape of the first tubular element 22 formedduring extrusion. Further, it is also contemplated that the material maybe extruded by alternative methods other than through die heads 32having extrusion apertures 34. It is contemplated that the extrusion mayoccur through any shaped space such that the extruded material acquiresa cross-sectional shape which is substantially the same as the shape ofthe shaped space during extrusion.

By way of example and not limitation, it is contemplated that theextruded material may alternatively be a thermosetting polymer or anyother material that may be appreciated by one of ordinary skill of theart that does not depart from the spirit of the present disclosure.Further, the material may be any polymer that falls within the scope ofthe materials discussed above, that will not chemically react withconcrete so as to substantially weaken the polymer or the concreteduring the lifespan of the use of the polymer within the concrete.

The first tubular element 22 may be formed via extrusion to have acircular cross sectional configuration in a plane perpendicular to alongitudinal axis, so as to resemble a traditional pipe or tube. Thiscircular configuration allows for less material to be used in order tomanufacture the first tubular element 22, thus reducing cost.Alternatively, the first tubular element 22 may be formed via extrusionto have a quadrangular configuration.

As shown in FIG. 5, the coupler 12 of the concrete dowel placementsystem 10 further includes a second tubular element 36 of a differentdimensional size than the first tubular element 22. The second tubularelement 36 includes an outer sleeve 25 and an inner sleeve 27 definingan aperture 29 extending along the entire length of the outer sleeve 25.The second tubular element 36 further includes at least onereinforcement wall between the inner sleeve 27 and the outer sleeve 25.The second tubular element 36 may differ from the first tubular element22 in size only, and thus, the cross-sectional configuration depicted inFIG. 2 may also be representative of a cross-sectional view of anexemplary embodiment of the second tubular element 36, albeit on adifferent scale. It is further contemplated that the second tubularelement 36 may be formed via extrusion as described herein. Morespecifically, the second tubular element 36 may be formed via extrusionthrough an extrusion die head 32 or by any other form of extrusion thatwould be appreciated by a person of ordinary skill in the art.

With regard to the first tubular element 22 and second tubular element36, it is further contemplated that at least one of the first tubularelement 22 and the second tubular element 36 may be formed to have adiameter of slightly less than five-eighths inches so that a slip dowel56 with a diameter of about five-eighths inches may be used with theconcrete dowel placement system 10 as will be discussed in furtherdetail herein. Although, it is also contemplated that neither the firsttubular element 22 nor the second tubular element 36 is aboutfive-eighths inches, but rather is of some other dimensional size.Additionally, the second tubular element 36 may be formed to have thesame configuration as the first tubular element 22, but it is alsocontemplated that the configurations of the first tubular element 22 andthe second tubular element 36 may be different. By way of example andnot limitation, according to one embodiment, the first tubular element22 is formed to have a circular configuration while the second tubularelement 36 is formed to have a quadrangular configuration. Otheralternative configurations are also contemplated, such as oval orrounded rectangle configurations.

By the embodiment of a coupler 12 shown in FIG. 6, an end portion of theouter sleeve 25 of the second tubular element 36 is attached to an endportion of the outer sleeve 24 of the first tubular element 22 to formthe coupler 12. The first tubular element 22 and second tubular element36 may be attached at absolute ends, but it is also contemplated thatattachment may be achieved by inserting an end portion of the firsttubular element 22 into a hollow of an end portion of the second tubularelement 36.

The concrete dowel placement system 10 further includes an elongated,tubular, dowel-receiving sheath 14 (see FIGS. 1 and 12) having at leastone interior opening 38 extending along the entire length of the sheath14, the sheath 14 being slidably extensible over one of the firsttubular element 22 and the second tubular element 36 to frictionallyengage the sheath 14 to the coupler 12. The sheath 14 having an emptyand smooth interior opening 38 allows for the desired unrestrictedslippage of the slip dowel 56 within the sheath 14 once the slip dowel56 has been placed within a second concrete section 58. Further, thesheath 14 may be formed to have a longitudinal length of about twelveinches so that a slip dowel 56 may be advanced twelve inches into asection of concrete as will be discussed in further detail herein, butit is alternatively contemplated that any other length sufficient forplacing a slip dowel 56 may be used.

It is contemplated that the sheath 14, similar to other components ofthe concrete dowel placement system 10, may be formed via extrusionthrough an extrusion die head or any other process of extrusion thatwould be known by a person of ordinary skill in the art, such as theprocesses described above. Further, it is contemplated that the sheath14 may be formed via extrusion to include a completely smooth outersurface 40, but it is also contemplated that the outer surface 40 of thesheath 14 may be formed to be not completely smooth. For example, thesheath 14 may be formed via extrusion to include at least one or aplurality of elements on the outer surface 40 of the sheath 14 thatextend along the longitudinal axis of the sheath 14. Such elements mayinclude linear rib protrusions 42 or linear grooves. The outer surface40 of the sheath 14 may be formed to also include raised or groovedhelical elements 44. FIG. 7 shows a cross-sectional view of anembodiment of a sheath 14 including rib protrusions 42 on the outersurface 40 of the sheath 14. Additionally, FIG. 8 is an upperperspective view of a sheath 14 that includes a raised helical element44 on the outer surface 40 of the sheath 14. In a similar vein, it iscontemplated that the sheath 14 may be formed via extrusion to include asinusoidal outer surface 40 on the sheath 14 or a helical uneven outersurface 40 on the sheath 14. The external features formed on the outersurface of the sheath, e.g., ribs or raised elements, may mitigatecracks formation in the concrete.

The aforementioned elements and characteristic features that may beformed on the outer surface 40 of the sheath 14 allow for improvedattachment between the concrete and the sheath 14, as concrete is moreprone to cracking when it is attached to completely smooth surfaces. Asecure, crack-resistant attachment between the sheath 14 and theconcrete is critical because the secure attachment allows the slip dowel56 to slide within the sheath 14 without disrupting the functionality ofthe sheath 14 as will be discussed in more detail below. To clarify howthe sheath 14 may engage the coupler 12, FIG. 9 shows a frontcross-sectional view of an embodiment of a concrete dowel placementsystem 10 where a sheath 14 has been slibably extended over a coupler12.

The concrete dowel placement system 10 may also include an end cap 20attachable to an end portion of the sheath 14 to completely cover theinterior opening 38 at the end of the sheath 14. The end cap 20 helpsprevent pourable concrete from entering the interior opening 38 of thesheath 14 while the concrete hardens. The end cap 20 may be a element ofduct tape or construction tape, a cap, a plug, a element of film, or anyblockade that is either permanently affixed or removably attached to thedistal end of the sheath 14.

An additional embodiment of the disclosure relates to another method ofconstructing a coupler 12. Now referring to FIGS. 10 and 11, in thisembodiment, the coupler 12 may be formed by first extruding a material,such as a polymer, to form a tubular element 46 having a first lengthportion 48 and a second length portion 50. The tubular element 46further includes at least one interior opening 38 extending along theentire length of the tubular element 46. By way of example and notlimitation, FIG. 10 illustrates a cross-sectional view of an exemplaryembodiment of a tubular element 46.

Next, as FIG. 11 shows, this method includes removing some of thematerial from the first length portion 48 of the tubular element 46 sothat the first length portion 48 of the tubular element 46 is of adifferent dimensional size than the second length portion 50 of thetubular element 46, thus ultimately forming a coupler 12.

By way of example and not limitation, the step of removing some of thematerial from a first length portion 48 of the tubular element 46 may beby lathing, milling, or computer numerical control machining devices.

Now referring to FIGS. 12 and 13, the concrete dowel placement system 10discussed above may be used to form a concrete structure, however,before any concrete is poured, at least one coupler 12 is affixed to aform section 16. A form is used to define the shape of the concrete onceit hardens. The coupler 12 may be affixed using a securing device 18.The securing device 18 may be a nail, screw, or any other device similarin nature so that the coupler 12 may be securely affixed to the formsection 16. Alternatively, the coupler 12 may also be affixed to theform section 16 using adhesive placed on a proximal end of the coupler12, or any other appropriate method of attachment that would beappreciated by one of ordinary skill of the art. According to variousaspects of the present disclosure, the configuration of the coupler 12and the corresponding sheath 14 allows the coupler 12 to be formedwithout a flange at the end portion which abuts the form section 16.Thus, the outer sleeve 24 of each tubular element of the coupler 12 maydefine the maximum outer diameter of the coupler 12, and the tubularelements themselves are capable of withstanding the forces associatedwith pouring concrete around the sheath 14. In a contemplatedembodiment, to prepare to pour a large section of concrete, a pluralityof couplers 12 is affixed to the form section 16 in a straight line; theline may run generally parallel to the underlying support surface 54.

It is to be appreciated that the form section 16 to which the couplers12 are attached is part of a complete form used to dictate the shape ofthe concrete once the concrete hardens. That is, the form section 16 ispart of a complete form that forms a boundary for concrete that ispoured within the boundary.

The form is arranged upon the underlying support surface 54 so thatconcrete remains within the boundary defined by the form when theconcrete is poured within the form. The form may be made of wooden studsor planks, plastic slabs, or any supports that will not chemically reactwith the concrete in a way that adversely affects the shape orstructural integrity of the concrete.

A sheath 14 is slidably disposed over each of the couplers 12 and may beheld in place by friction or by other means of attachment, such asadhesives. One of ordinary skill in the art will appreciate that the fitbetween each coupler 12 and its corresponding sheath 14 is tight andsealed enough so that it is unlikely that pourable concrete can leakinto the sheaths 14 when the concrete is poured. Concrete leaking intothe interior of the sheaths 14 can negatively impact one of thefunctions of the concrete dowel placement system 10, which is to allowslip dowels 56 to slide freely within the sheaths 14. Further,regardless of the method used to secure the coupler 12 to the formsection 16, it is contemplated that the secure and sealed connectionbetween the coupler 12 and the form section 16 can be maintained duringthe pouring of the concrete and until the concrete hardens. That is, theconnection between the coupler 12 and sheath 14 is strong enough suchthat the pouring of the concrete does not break or disrupt theconnection.

An attachable end cap 20 may be disposed on a distal end of the sheath14 to completely cover the opening 38 at the end of the sheath 14 toprevent pourable concrete from leaking into the interior of the sheath14 after the concrete is poured over the concrete dowel placement system10.

Now referring to the cross-sectional view of two different orientationsof a concrete dowel placement system 10 of FIGS. 13 and 14, the coupler12 may have at least two positional orientations. As shown in FIG. 13,in one orientation, the smaller end of the coupler 12 is affixed to theform section 16. The smaller end may have a diameter or cross-sectionalarea that is smaller than the diameter or cross-sectional area of thebigger end. This permits a sheath 14 with an interior size similar tothe bigger end of the coupler 12 to slidably engage the bigger end ofthe coupler 12. Alternatively, as shown in FIG. 14, a bigger end portionof the coupler 12 may be affixed to the form section 16. In this case, asheath 14 with an interior size similar to the size of the smaller endof the coupler 12 may slidably engage the smaller end of the coupler 12.Thus, the coupler 12 may have at least two different orientations uponthe form section 16 to allow connectability with at least two differentsheaths 14 having different dimensions. It is to be appreciated thatregardless of the positional orientation of the coupler 12, theconnection between the coupler 12 and the sheath 14 is tight and sealedenough to prevent pourable concrete from substantially intruding intothe interior of the sheath 14.

Next, concrete may be poured within a first form. Now referring to FIG.15, concrete is poured onto the underlaying support surface 54 andwithin the first form. The poured concrete makes contact with the sheath14 and the end cap 20. It is contemplated that the pourable concrete maycompletely cover the outer surfaces 40 of the sheath 14 and the end cap20 that are exposed to the pourable concrete. Once the concrete hardens,this portion of concrete is a first concrete section 52. The concrete ofthe hardened first concrete section 52 affixes to the sheath 14 toprevent movement between the sheath 14 and the hardened first concretesection 52. As shown in FIG. 15, after the first concrete section 52 isestablished, the interior of the sheath 14 remains hollow exceptpossibly for a portion of the end cap 20 which may be disposed within anend portion of the sheath 14 if the end cap 20 is in the form of, forexample, a plug. The empty interior of the sheath 14 allows a slip dowel56 to be inserted within the sheath 14 at a later time.

Referring to FIGS. 16 and 17, after the first concrete section 52hardens, the form section 16 and coupler 12 are removed. The removal ofthe form section 16 and coupler 12 exposes an edge surface of the firstconcrete section 52, the edge surface allowing access to the interior ofthe sheath 14. Thus, a slip dowel 56 may be advanced into the sheath 14as shown in FIG. 17.

The slip dowel 56 may be a smooth steel rod, but it is contemplated thatthe slip dowel 56 may be made of aluminum, iron, or any other suitablemetal or metal alloy strong enough to endure longitudinal or verticalcompression and expansion forces that may occur between sections ofconcrete without bending substantially. Further, the entire outersurface of the slip dowel 56 need not be smooth. For example, a lengthportion of the slip dowel 56 may include a ribbed outer surface, similarto the outer surface of typical re-bar, or include other features on theouter surface such that the slip dowel 56 is unsmooth. It is furthercontemplated that the edge surface of the first concrete section 52allows access to a plurality of interior openings 38 of sheaths 14aligned generally in parallel within the first concrete section 52, thusallowing for a plurality of generally parallel-aligned slip dowels 56 tobe inserted into sheaths 14.

The slip dowel 56 may be fully advanced within the sheath 14 so as tomake contact with the end cap 20, but it is also contemplated that theslip dowel 56 may be only partially advanced within the sheath 14 toallow space between the inserted end of the slip dowel 56 and the endcap 20. The space can help prevent undesirable pressure within the firstconcrete section 52 and the second concrete section 58 that may becaused by the slip dowel 56 pressing against the end cap 20 when theconcrete expands. Such pressure can potentially expedite undesirableweakening of the concrete.

The slip dowel 56 projects into an area immediately adjacent to thefirst concrete section 52 to define an exposed segment, allowing for asecond concrete section 58 to be poured over the exposed segment of theslip dowel 56.

Now referring to FIG. 18, next, the second concrete section 58 may beformed. A second form is prepared and disposed upon the underlayingsupport surface 54, bounding the area immediately adjacent to the firstconcrete section 52 and encompassing the exposed segments of the slipdowels 56. Then, concrete is poured within the second form and theconcrete is allowed to make contact with the exposed segments of theslip dowels 56. The concrete may also completely cover the outersurfaces of the slip dowels 56. After the concrete hardens, this portionof concrete is the second concrete section 58 and the form may beremoved.

Since the edge surface of the second concrete section 58 that makescontact with the edge surface of the first concrete section 52 hardensat a different time than the edge surface of the first concrete section52, a cold joint 60 forms at the interface.

In contrast to the first concrete section 52, which includes a sheath 14and an end cap 20 disposed within, the second concrete section 58 has noportion of a concrete dowel placement system 10 disposed within, andthus makes contact with the slip dowels 56. This contact with the slipdowels 56 allows the second concrete section 58 to adhere to the slipdowels 56, thus prohibiting movement between the slip dowels 56 and thesecond concrete section 58. This adhesion allows the slip dowels 56 toslide longitudinally within the sheaths 14 and across the cold joint 60.As the first concrete section 52 and the second concrete section 58expand and contract, the second concrete section 58 holds onto to theslip dowels 56 while the sheaths 14 disposed within the first concretesection 52 allow the slip dowels 56 to slide back and forth freelywithin the sheaths 14.

The ability for the slip dowels 56 to slide freely within the sheaths 14aids in preventing buckling and bulging of the concrete at the coldjoint 60. Buckling and bulging is often undesirable because it canresult in cracks in the concrete, thus reducing the structural integrityof the concrete, and in the case of a pedestrian application, can pose asafety hazard by increasing the risk of people tripping on the cracks.Cracks and bulging in the concrete may also be considered aestheticallyunappealing.

The ability for the slip dowels 56 to slide freely within the sheaths 14also allows the interface between the first concrete section 52 and thesecond concrete section 58 to remain aligned, thus preventing faulting,i.e., undesirable skewing of the first concrete section 52 and thesecond concrete section 58 at the cold joint 60. Skewing at the coldjoint 60 may damage the concrete, weaken the concrete, or result inundesirable aesthetics.

Referring now to FIGS. 19-21, there is depicted yet another embodimentof a coupler 100 including a tubular element 102 including an innersleeve 104 and a plurality of splines 106 extending along the innersleeve 104. Notably, the coupler in FIGS. 19-21 does not include anouter sleeve coaxially disposed relative to the inner sleeve 104.Rather, the splines 106 extend radially outward from the inner sleeve104 to provide an outer engagement surface adapted to frictionallyengage the sheath 108. The use of splines 106, rather than an outersleeve, may allow the coupler 100 to be formed using less material, andthus, cost savings may be achieved.

The inner sleeve 104 depicted in FIGS. 19-21 is a cylindrical tubedisposed about a central axis 110, and thus, includes an inner surface112 defining an aperture 114 extending along the length of the innersleeve 104. The aperture 114 is sized and configured to receive afastener 116, such as a nail, screw, or the like for securing thecoupler 100 to the concrete form 118. The inner sleeve 104 includes afirst end 120 and an opposing second end 122, wherein the first end 120is adapted to be disposed in abutting contact with the concrete form 118when the coupler 100 is attached thereto.

The plurality of splines 106 are coupled to the inner sleeve 104, witheach spline 106 extending radially outward from an outer surface 124 ofthe inner sleeve 104, so as to define a coupler outer diameter, D. Thecoupler 100 is configured such that the outer diameter D is sized andconfigured so as to enable the sheath 108 to be advanced over thecoupler 100, with an inner surface 126 of the sheath 108 frictionallyengaging with the splines 106. Each spline 106 also extends axiallyalong the outer surface 124 of the inner sleeve 104 between the firstand second ends 120, 122 thereof. In the exemplary embodiment, thecoupler 100 includes eight splines 106 spaced evenly around the outercircumference of the inner sleeve 104, e.g., the splines 106 are spacedapart by about 45 degrees. As shown in FIGS. 19 and 21, the splines 106extend completely between the first and second ends 120, 122, with thesplines 106 having a beveled surface 128 adjacent the second end 122.However, it is understood that in other implementations, the splines 106may extend only partially between the first and second ends 120, 122.

The coupler 100 may be formed via extrusion, wherein an extrusion diehaving an opening corresponding to the cross section depicted in FIG. 20is used to form the coupler 100, as described in more detail above. Ofcourse, other materials and manufacturing techniques may also be usedwithout departing from the spirit and scope of the present disclosure.

FIGS. 19-21 show the coupler 100 being of a substantially uniformconfiguration between the first and second ends 120, 122 thereof. Inthis respect, the outer diameter D is substantially uniform along thelength of the coupler 100. Thus, the coupler 100 is adapted for use witha sheath 108 having an inner opening that is of a specific diameter,which corresponds to the outer diameter D of the coupler 100.

However, referring now to FIG. 22, there is depicted another embodimentof a coupler 200 including a first tubular element 202 defining a firstouter diameter, D₁, and a second tubular element 204 defining a secondouter diameter, D₂, greater than the first outer diameter D₁. The firstand second tubular elements 202, 204 are coupled to each other at ajoint 205, either through the use of an adhesive, or other joiningelements known in the art. The first tubular element 202 includes afirst inner sleeve 206 and a plurality of first splines 208, while thesecond tubular element 204 includes a second inner sleeve 210 and aplurality of second splines 212. The plurality of first splines 208define the first outer diameter D₁, and the plurality of second splines212. define the second outer diameter D₂. The first tubular element 202defines a first abutment end 214, while the second tubular element 204defines a second abutment end 216, with the first and second abutmentends 214, 216 each being adapted to be positioned in abutting contactwith a concrete form 118, depending on the intended use of the coupler200, e.g., whether the coupler 200 is to be used with a sheath adaptedto frictionally engage the outer surface of the splines 208 on the firsttubular element 202, or the splines 212 on the second tubular element204. In particular, if the coupler 200 is to be used with a sheath whichengages with splines 208 on the first tubular element 202, the coupler200 is attached to the form 118 with the second abutment end 216 coupledto the form, and the first tubular element 202 extending away from theform. Conversely, if the coupler 200 is to be used with a sheath whichengages with splines 212 on the second tubular element 204, the coupler200 is attached to the form 118 with the first abutment end 214 coupledto the form, and the second tubular element 204 extending away from theform.

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the embodiments of the present disclosureonly and are presented in the cause of providing what is believed to bethe most useful and readily understood description of the principles andconceptual aspects of the present disclosure. In this regard, no attemptis made to show structural details of the present disclosure in moredetail than is necessary for the fundamental understanding of thepresent disclosure, the description taken with the drawings makingapparent to those skilled in the art how the several forms of thepresent disclosure may be embodied in practice.

1. A method of constructing a concrete dowel placement system, themethod comprising: constructing a coupler, the constructing comprising:extruding a polymer to form a first tubular element; extruding a polymerto form a second tubular element, the second tubular element having adimensional size different from a dimensional size of the first tubularelement; attaching an end portion of the second tubular element to anend portion of the first tubular element; and extruding a polymer toform an elongated, tubular, dowel-receiving sheath, the sheath having atleast one interior opening extending along the entire length of thesheath and the sheath being configured to be slidably extensible overthe coupler to frictionally engage one of the first tubular element andthe second tubular element.
 2. The method of claim 1, further comprisingthe step of attaching an end cap to an end portion of the sheath tocompletely cover the at least one interior opening at an end of thesheath.
 3. The method of claim 1, wherein the step of extruding apolymer to form the first tubular element includes forming a body havinga circular cross-sectional configuration along a longitudinal axisduring extrusion of the polymer.
 4. The method of claim 1, wherein thestep of extruding a polymer to form the first tubular element includesforming the first tubular element to have an inner sleeve and aplurality of splines extending radially outward from the inner sleeveand longitudinally along the inner sleeve.
 5. The method of claim 4,wherein the step of extruding a polymer to form the second tubularelement includes forming the second tubular element to have an innersleeve and a plurality of splines extending radially outward from theinner sleeve and longitudinally along the inner sleeve.
 6. The method ofclaim 1, wherein the first tubular element defines opposed first tubularelement end portions having maximum outer diameters approximately equalto each other, and the second tubular element defines opposed secondtubular element end portions having maximum outer diametersapproximately equal to each other.
 7. The method of claim 1, wherein thestep of extruding a polymer to form the first tubular element includesforming an inner sleeve, an outer sleeve, and at least one reinforcementwall extending therebetween.
 8. The method of claim 1, wherein the stepof extruding a polymer to form a sheath includes forming at least onelinear rib protrusion along a longitudinal axis of the sheath on anouter surface of the sheath during extrusion of the polymer.
 9. Themethod of claim 1, wherein the step of extruding a polymer to form thesheath includes forming at least one raised helical element on an outersurface of the sheath during extrusion of the polymer.
 10. The method ofclaim 1, wherein the step of extruding a polymer to form the sheathincludes forming a helical uneven outer surface on the sheath duringextrusion of the polymer.
 11. A concrete dowel placement systemcomprising: a coupler comprising: a first tubular element comprising: aninner sleeve disposed about a central axis to define an aperture; and anouter body disposed radially outward of the inner sleeve; a secondtubular element comprising: an inner sleeve disposed about a centralaxis to define an aperture; and an outer body disposed radially outwardof the inner sleeve; an end portion of the outer element of the secondtubular element being attached to an end portion of the outer element ofthe first tubular element; and an elongated, tubular, dowel-receivingsheath having at least one interior opening extending along the entirelength of the sheath and being slidably extensible over the coupler tofrictionally engage one of the first tubular element and the secondtubular element.
 12. The system of claim 11, wherein the outer body ofthe first tubular element includes a plurality of splines extendinglongitudinally along the inner sleeve.
 13. The system of claim 11,further comprising an end cap attachable to an end portion of the sheathto completely cover the at least one opening at an end of the sheath.14. The system of claim 11, wherein the sheath further comprises atleast one linear rib protrusion along a longitudinal axis of the sheathon an outer surface of the sheath.
 15. The system of claim 11, whereinthe sheath further comprises at least one helical element on an outersurface of the sheath. 16-20. (canceled)